System and method for multi-mode radio operation

ABSTRACT

Described is a system having a mobile station and an access point which connects the mobile station to a network. The mobile station has a first mode of operation and a second mode of operation. In the first mode of operation, the mobile station transmits a data packet intended for a further mobile station to the access point and the access point transmits the data packet to the further mobile station. In the second mode of operation, the mobile station transmits the data packet intended for the further mobile station directly to the further mobile station.

BACKGROUND

A conventional system may utilize a mobile unit that transmits andreceives signals according to a wireless communication protocol (e.g.,the IEEE 802.11 standard). The IEEE 802.11 standard defines twodifferent types of networks: an ad-hoc network, or independent basicservice set (“IBSS”), and an infrastructure network, or extended serviceset (“ESS”). In the infrastructure network, the mobile unit communicateswith a further mobile unit or network device through an access point inconjunction with a distribution system (e.g., WAN, WWAN, LAN, WLAN, PAN,WPAN, etc.). Whereas, in the ad-hoc network, the mobile unitcommunicates directly with a further mobile unit or other networkdevice.

Under the 802.11 standard, the ad hoc network and the infrastructurenetwork are mutually exclusive of each other. That is, if the mobileunit desired to connect to a printer, the printer could be added to theinfrastructure network, thereby becoming a network resource available tothe entire network. The mobile unit would communicate with the printervia the access point. In contrast, the mobile unit may establishexclusive communication with the printer by first disconnecting from theinfrastructure network and switching to the ad-hoc network, where themobile unit communicates directly with the printer without utilizing theaccess point.

As currently implemented, the infrastructure network and the ad-hocnetwork have inherent disadvantages. For example, if the printer isadded to the infrastructure network, data sent to the printer adds anadditional load to network traffic, and the printer is subject tounwanted network activity. However, if the printer communicates with themobile unit in an ad-hoc network, the mobile unit must disconnect fromthe infrastructure network. Thus, there presents a need for asimultaneous infrastructure/ad-hoc operating mode, or simultaneous basicservice set (“SBSS”), whereby the mobile unit can maintain connection tothe infrastructure network, while sending data directly to the printer.

SUMMARY OF THE INVENTION

A system having a mobile station and an access point which connects themobile station to a network. The mobile station has a first mode ofoperation and a second mode of operation. In the first mode ofoperation, the mobile station transmits a data packet intended for afurther mobile station to the access point and the access pointtransmits the data packet to the further mobile station. In the secondmode of operation, the mobile station transmits the data packet intendedfor the further mobile station directly to the further mobile station.

In addition, a mobile station having a processor and a memory storing aset of instructions for execution on the processor. The set ofinstructions comprises a first mode of operation and a second mode ofoperation. In the first mode of operation, the mobile station transmitsa data packet intended for a further mobile station to an access pointconnected to a network, and the access point transmits the data packetto the further mobile station. In the second mode of operation, themobile station transmits the data packet intended for the further mobilestation to the further mobile station.

Furthermore, a method for checking a field of a media access controlframe transmitted to a mobile station, adjusting transmission power ofthe mobile station based on a value in the field and transmitting a nextmedia access control frame using the adjusted transmission power.

A method for sending a data packet destined for a mobile unit to anaccess point, listening for one of a transmission of the data packet bythe access point to the mobile unit and a transmission of anacknowledgment by the mobile unit to the access point, adding an addressof the mobile unit to a table when the one of the listened fortransmissions is detected and sending a further data packet destined forthe mobile unit directly to the mobile unit when the address is presentin the table.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary embodiment of a system utilizing a first mode ofoperation according to the present invention.

FIG. 2 is an exemplary embodiment of the system of FIG. 1 utilizing boththe first mode of operation and a second mode of operation according tothe present invention.

FIG. 3 is an exemplary embodiment of an architecture of a mobile stationaccording to the present invention.

FIG. 4 is an exemplary embodiment of a MAC frame according to thepresent invention.

FIG. 5 is a detailed view of a frame body of the MAC frame of FIG. 4.

FIG. 6 is a detailed view of a frame control field of the frame body ofFIG. 5.

FIG. 7 is a table of type values and associated descriptions accordingto the present invention.

FIG. 8 is a table of subtype values and associated descriptionsaccording to the present invention.

FIG. 9 is an exemplary embodiment of the system using a first mode ofoperation according to the present invention.

FIG. 10 is an exemplary embodiment of the system of FIG. 9 using asecond mode of operation according to the present invention.

FIG. 11 is an exemplary embodiment of the system of FIG. 10 reverting tothe first mode of operation.

FIG. 12 is ane exemplary embodiment of a table of hardware addressesaccording to the present invention.

FIG. 13 is an exemplary embodiment of a method for adding a hardwareaddress to the table of a receiving mobile station.

FIG. 14 is an exemplary embodiment of a method for determining whichmode of operation to use according to the present invention.

FIG. 15 is an exemplary embodiment of a method for transmitting a datapacket according to the present invention.

FIG. 16 is an exemplary embodiment of a method for entering the hardwareaddress of the mobile station in the table of a further mobile stationaccording to the present invention.

FIG. 17 is an exemplary embodiment of a pairing timer according to thepresent invention.

FIG. 18 is an exemplary embodiment of a power adjustment mechanism forthe mobile station receiving the data packet according to the presentinvention.

FIG. 19 is an exemplary embodiment of the power adjustment mechanism ofFIG. 18 for the mobile station transmitting the data packet according tothe present invention.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. As shown in FIG. 1,the present invention includes a system 5 which provides for amulti-mode radio operation. The system 5 includes a wireless network 10(e.g., WLAN, WPAN) that is connected to an access point 15 (“AP”).According to the present invention, a first mobile station 20 (“MS”)(e.g., PC, laptop, cell phone, PDA, hand-held computer, radiotransceiver, etc.) may desire to communicate with a second MS 25. Thefirst MS 20 and the second MS 25 operate according to an existingcommunication protocol, such as the IEEE 802.11 standard. As such, boththe first MS 20 and the second MS 25 may have similar functionality,capabilities and components (e.g., processors, antennas, memory, etc.),including those described herein. In other embodiments of the presentinvention, the second MS 25 may be a receiver device (e.g., a printer, aheadset, etc.). Though the invention may be described with regard to thefirst MS 20, those skilled in the art would understand that the presentinvention may be applied to any radio transceiver communicating over anetwork. Thus, the terms “first” and “second” are not limiting, but onlyprovided for clarity and illustration of the exemplary embodiments ofthe invention.

The first MS 20 has a first mode of operation, which is based on theexisting communication protocol, such as the IEEE 802.11 standard. Inthe first mode of operation, the first MS 20 desires to send a datapacket to the second MS 25. As is known in the art, and according to the802.11 standard (e.g., the infrastructure network), the first MS 20transmits the data packet to the AP 15 that is associated with the firstMS 20. If the first MS 20 and the second MS 25 are associated with theAP 15, the AP 15 then transmits the data packet to the second MS 25.However, if the second MS 25 is not associated with the AP 15, the AP 15transmits the data packet to the wireless network 10, which, in turn,transmits the data packet to a further AP which is associated with thesecond MS 25. As would be understood by those skilled in the art, anynumber of APs may be connected to the wireless network 10.

The transmission of the data packet from the first MS 20 to the AP 15,in a wireless setting such as described herein, is known in the art as a“hop.” Thus, according to the 802.11 standard, the minimum number ofhops that is required to transmit the data packet from the first MS 20to the second MS 25 is two hops: one hop from the first MS 20 to the AP15, and a second hop from the AP 15 to the second MS 25. The minimum twohops happens only when the AP 15 is associated with the first MS 20 andthe second MS 25.

The first MS 20 is further capable of utilizing a second mode ofoperation, shown in FIG. 2, based on the existing communicationprotocol. In the second mode, and according to the present invention,the first MS 20 intends to transmit the data packet to the second MS 25.However, in the second mode, the transmission of the data packet can beaccomplished in one hop. That is, the first MS 20 can transmit the datapacket directly to the second MS 25, without having to utilize the AP15. As will be described herein, the second mode of operation is usableunder certain conditions. However, the present invention allows thesimultaneous use of both the first and second modes by the MSs 20,25.Thus, the first MS 20 may not have to disconnect from the wirelessnetwork 10 when communicating directly with the second MS 25.

With reference to FIG. 2, the first MS 20 and the second MS 25 may bepaired to form a local cell 30. As would be understood by those skilledin the art, the local cell 30 is defined by a communicable range inwhich the first MS 20 can transmit and receive radio frequency (“RF”)signals. The local cell 30 may be located within an AP cell 35 which isdefined by an RF transmit/receive range of the AP 15. To successfullycommunicate using the second mode of operation, the second MS 25 must bewithin the local cell 30 (i.e., MS 20 and MS 25 are within communicablerange of each other). However, as will be described below, the MS 20 mayremain in the second mode even if the MS 25 moves out of communicablerange.

Forming the local cell 30 may be accomplished in several ways. In oneexemplary embodiment, the first MS 20 may be manually paired to thesecond MS 25. Manual pairing may be accomplished by, for example,entering a hardware address of the second MS 25 into a table 200, ornear-list, contained within the first MS 20, which is shown in FIG. 12and described below. As would be understood by those skilled in the art,the term “hardware address” may be used to describe any unique addressassociated with a mobile device, for example, a media access control(“MAC”) address and/or basic service set identification (“BSSID”)throughout the application. Those terms may be used interchangeablythroughout this description. The table 200 may further include a set ofparameters associated with the hardware address. In this exemplaryembodiment, the first MS 20 may be a mobile computer that is manuallypaired to the second MS 25 which is a dedicated printer. In this manner,the first MS 20 and the second MS 25 may only look for and communicatewith each other. Any other activity in the AP cell 35 may go through theAP 15. However, in the same embodiment the MSs 20,25 may receivetransmissions from other MSs within the AP cell 35.

As would be understood by those skilled in the art, the local cell 30may further include any other MSs that are in communicable range withthe first MS 20. The first MS 20 may be manually paired with any numberof other MSs that are within the local cell 30 at a given time. Hardwareaddresses for the other MSs may be manually entered into the table 200of the first MS 20. For example, the first MS 20 may be the mobilecomputer which is manually paired to the second MS 25 which is thededicated printer. The local cell 30 formed by the first MS 20 and thesecond MS 25 may further include a further MS which may be a datacapture device (e.g., bar code scanner, RFID reader, Magstripe reader,etc.).

In a further embodiment, the local cell 30 may be formed automatically.In this embodiment, the first MS 20 can monitor and track any MS thatcomes within the local cell 30. For example, if the second MS 25 islocated within the AP cell 35, but not within the communicable range ofthe first MS 20, the hardware address of the second MS 25 will not be inthe table 200 of the first MS 20. However, when the second MS 25 movesinto the communicable range of the first MS 20, the first MS 20 mayinclude the hardware address of the second MS 25 in the table 200. Thisprocess will be described in further detail below.

FIG. 3 shows an exemplary embodiment of a computing architecture 37 ofthe first MS 20. The architecture 37 allows the first MS 20 to utilizethe first and second modes of operation. Specifically, the architecture37 allows the first MS 20 to communicate directly with the second MS 25without disconnecting from the wireless network 10. Operation of thecomputer architecture 37 will be described in further detail below.

According to the present invention, transmission of a data packet fromthe first MS 20 to the second MS 25 may be accomplished using a MACframe 40, an exemplary embodiment of which is seen in FIG. 4. The MACframe 40 includes a frame header 50, a frame body 55 and a frame checksequence (“FCS”) 60. The frame header 50 typically has a 30 bytecapacity, while the frame body 55 has a 2312 byte capacity and the FCS60 has a 6 byte capacity. Each MAC frame 40 may correspond to adifferent function. For example, the MAC frame 40 may be used for acontrol function, a management function or a data function. As would beunderstood by those skilled in the art, the frame body 55 may change(e.g., capacity, format, content, etc.) based on the function to beaccomplished.

The frame header 50 of the MAC frame 40 is shown in further detail inFIG. 5. Components and properties of the frame header 50 are generallyknown in the art. The frame header 50 includes a frame control field 65adjacent to a duration/identification field 70, each of which may have a2 byte capacity. The duration/identification field 70 for the datafunction represents the duration of the MAC frame 40, whereas for thecontrol function, the field 70 represents an identity of the wirelessstation that initiated the transmission. A first address field 75follows the duration/identification field 70 and represents a sourceaddress of the transmission (e.g., the hardware address of the first MS20). A second address field 80 adjacent to the first address field 75represents a destination address of the transmission (e.g., the hardwareaddress of the second MS 25). A third address field 85 adjacent to thesecond address field 80 represents a receiving station address. As shownin FIG. 5, a sequence control field 90 may be adjacent to the thirdaddress field 85. The sequence control field 90 may have a 2 bytecapacity. A fourth address field 95 represents a transmitting stationaddress. In an exemplary embodiment, each address field 75,80,85,95 mayhave a 6 byte capacity, but the present invention may be implementedregardless of the size.

An expanded view of the frame control field 65 is shown in FIG. 6. Asnoted above, the frame control field 65 has a 2 byte capacity, and theexpanded view shows a bit-by-bit view. A protocol version field 100 isshown as the first portion of the frame control field 65. The protocolversion field 100 is typically set to zero. A type field 105 and asubtype field 110 follow the protocol version field 100, and togetherdescribe the function (e.g., data, control, management) of the MAC frame40. A “to DS” field 115 is adjacent to the subtype field 110. When the“to DS” field 115 has a one value, the MAC frame is transmitted to thedistribution system. Adjacent to the “to DS” field 115 is a “from DS”field 120. When the “from DS” field 120 has a one value, the MAC framehas come from the distribution system.

Further included in the frame control field 65 is a “more frag” field125, which is located adjacent to the “from DS” frame 120. A one valuein the “more frag” field 125 represents that one or more fragment framesmay follow, whereas a zero value represents that this MAC frame 40 is anunfragmented frame or a last MAC frame. Adjacent to the “more frag”field 125 is a retry field 130, which, if a one value is present,indicates that this MAC frame 40 is a retransimission. A powermanagement field 135 is seen disposed adjacent to the retry field 130. Aone value indicates that the wireless station is in active mode, whereasa zero value indicates that the wireless station is in a power-save mode(e.g., sleep mode).

Further included in the frame control field 65 is a “more data” field140, which is disposed adjacent to the power management field 135. A onevalue in the “more data” field 140 indicates that an additional MACframe(s) is buffered with the intention to be sent to the destinationaddress of the transmission. A one value in a wired equivalent privacy(“WEP”) field 145 indicates that the data packet has been processed witha WEP algorithm. As understood by those skilled in the art, WEP is asecurity protocol for a WLAN, as defined in the 802.11 standard. A finalfield in the frame control field 65 is an order field 150, which, if aone value is present, indicates that the MAC frames must be strictlyordered when transmitted/received.

As noted above, the type field 105 together with the subtype field 110describe the function of the MAC frame 40. As seen in FIG. 7, a “00”type value indicates that the MAC frame 40 will perform the managementfunction; a “01” type value indicates a control function; a “10”indicates a data function. A “11” type value is designated as reserved,according to the 802.11 standard. Thus, using the reserved type, eachfunction (e.g., management, control, data) may have up to eight reservedsubtypes, those dedicated to the function (four) plus the reserved type(four). For example, the data function may have up to eight dedicatedsubtypes (e.g., 1000 hex through 1111 hex).

An exemplary embodiment of proposed type and subtype combinations isshown in FIG. 8. The subtype field 110 may comprise four bit values(i.e., b4-b7), each of which may indicate an event, status, setting,change, etc. For example, in the exemplary embodiment shown, the b6value may indicate a power change. As such, a power increase may beindicated by a zero value, whereas a power decrease value may beindicated by a one. In this manner, the b6 value may be used to signifyan increase or decrease in transmit power. The b7 value may be used toidentify to further wireless stations that this MAC frame 40 came fromthe wireless station operating according to the second mode ofoperation.

The first and second modes of operation will now be described in furtherdetail. As shown in FIG. 9, the system 5 includes the AP 15, the firstMS 20, the second MS 25 and a third MS 155. Each MS 20,25,155 has aradio frequency (“RF”) coverage area 160,165,170, respectively,associated therewith, which defines the range that the MS caneffectively transmit and receive RF signals. According to the first modeof operation, the first MS 20 intends to send a data packet to thesecond MS 25, but does not know that the second MS 25 is within thecoverage area 160 of the first MS 20. As such, the first MS 20 sends adata packet source signal 175 to the AP 15. The AP 15 sends an APacknowledgment signal 180 back to the first MS 20 confirming receipt ofthe data packet source signal 175. As would be understood by thoseskilled in the art, the AP 15 may not send the AP acknowledgment signal180 if, for example, the data packet source signal 175 has beendistorted, is unrecognizable or corrupted.

The AP 15 then relays the data packet to the second MS 25 using a datapacket destination signal 185. The second MS 25 sends an MSacknowledgment signal (“ACK”) 190 back to the AP 15 to confirm receiptof the data packet destination signal 185. According to the presentinvention, the first MS 20, after sending the data packet source signal175, begins listening for transmissions from other wireless stations(e.g., APs, MSs) within its RF coverage area 160. Specifically, thefirst MS 20 listens for the data packet destination signal 185 from theAP 15 and/or the MS acknowledgment signal 190 from the second MS 25. Thefirst MS 20 may not hear the data packet destination signal 185 if, forexample, the second MS 25 is not located within the AP cell 35. That is,if the second MS 25 is associated with a further AP connected to thenetwork 10, the AP 15 may transmit the data packet destination signal185 to the further AP via the network 10. Thus, the first MS 20 may nothear the data packet destination signal 185 transmitted from the furtherAP, which is outside of the local cell 30. Similarly, the first MS 20may not hear the MS acknowledgment signal 190 if the second MS 25 isoutside of the local cell 30.

If the first MS 20 hears one or both of the signals 185,190, the firstMS 20 may assume that the second MS 25 is within the RF coverage area160 of the first MS 20. As such, the first MS 20 may switch to thesecond mode of operation and may send a further data packet signal(s)195 directly to the second MS 25, without utilizing the AP 15. Thesecond MS 25 may then send the MS acknowledgment signal 190 to the firstMS 20, rather than the AP 15. If, however, the first MS 20 does not hearthe data packet destination signal 185 and/or the MS acknowledgmentsignal 190, then the first MS 20 may continue to send data packetsignals according to the first mode of operation (i.e., through the AP15). Also, if the first MS 20 sends the further data packet signal 195to the second MS 25 and does not receive the MS acknowledgment signal190 from the second MS 25, the first MS 20 may abort communication usingthe second mode of operation, and revert to the first mode of operation.This may happen when, for example, the second MS 25 moves out of the RFcoverage area 160 of the first MS 20.

After the first MS 20 has received an indication that the second MS 25is within the RF coverage area 160, the first MS 20 may include thehardware address of the second MS 25 in the table 200. Thus, the firstMS 20 may continue communicating with the second MS 25 using the secondmode of operation, until, for example, the second MS 25 moves out of theRF coverage area 160. However, the first MS 20 may maintain the hardwareaddress of the second MS 25 in the table 200 for a predetermined amountof time which will be explained further below. As shown in FIG. 10, thesecond MS 25 has re-entered the RF coverage area 160 of the first MS 20after temporarily moving out of the RF coverage area 160. The first MS20 retains the hardware address of the second MS 25 for a predeterminedtime after the hardware address is stored on the first MS 20. Thistiming will be described in greater detail below. Thus, the first MS 20may immediately initiate communication with the second MS 25 using thesecond mode of operation during this predetermined time period. That is,the first MS 20 does not have to wait to hear the MS acknowledgmentsignal 190 from the second MS 25 to initiate the second mode ofoperation. Thus, the first MS 20 may assume that the second MS 25remains within the RF coverage area 160 and send the data packet sourcesignal 175 directly to the second MS 25. If the first MS 20 receives theMS acknowledgment signal 190 from the second MS 25, the first MS 20thereby confirms the second MS 25 remains in the local cell 30 and cancontinue to transmit further data packet signals 195 using the secondmode. However, if the second MS 25 does not receive the data packetsource signal 175, for example, because the second MS 25 has moved outof the RF coverage area 160, the first MS 20 will revert to the firstmode to send the data packet as will be described below.

As shown in FIG. 11, the first MS 20 may send the data packet sourcesignal 175 or the further data packet signal 195 to the second MS 25,but the second MS 25 may have vacated the RF coverage area 160 of thefirst MS 20. Accordingly, the first MS 20 may attempt a predeterminednumber of retransmissions, with a uniform or exponential time interval(e.g., backoff) between each attempted retransmission. However, when thepredetermined number of retransmissions reaches zero, or thepredetermined time expires, the first MS 20 may remove the hardwareaddress of the second MS 25 from the table 200. Thus, the first MS 20may have to reacquire the hardware address of the second MS 25 at alater time, for example, when the second MS 25 moves back into the RFcoverage area 160 of the first MS 20.

A further embodiment of the present invention involves utilization ofthe second mode of operation by the second MS 25. In this embodiment,the first MS 20 has previously sent the data packet source signal 175and/or the further data packet signal 195 to the second MS 25. When thesecond MS 25 receives the signals 175,195, a logic circuit in the secondMS 25 checks the fourth address field 95 to determine the hardwareaddress of the wireless station that transmitted the data packet. Thoseof skill in the art will understand that the logic circuit as describedherein may be implemented in software or hardware. Furthermore, anywireless station, including the first MS 20, may include the logiccircuit described herein. If the fourth address field 95 has thehardware address of the AP 15 associated with the second MS 25, then thesecond MS 25 may assume that the first MS 20 is not within the RFcoverage area 165 of the second MS 25, and the second MS 25 maytransmit/receive data packets according to the first mode of operation.However, if the fourth address field 95 has the hardware address of thefirst MS 20, then the second MS 25 may assume that the first MS 20 istrying to initiate communication using the second mode of operation. Thesecond MS 25 may then add the hardware address of the first MS 20 to thetable 200 in the second MS 25 which lists the hardware addresses of anywireless station within the RF coverage area 165 of the second MS 25. Asnoted above, the second MS 25 may revert back to the first mode ofoperation after a predetermined number of failed retransmissions to thefirst MS 20 or a counter in the second MS 25 reaches zero or apredetermined number.

An exemplary embodiment of the table 200 is shown in FIG. 12. The table200 will be described with reference to the first MS 20, but those ofskill in the art will understand that any wireless station may includethe table 200. The table 200 may include a hardware address field 205, atimer field and/or retransmission field 210. The hardware address field205 may include the hardware addresses of any of the wireless stations(e.g., the AP 15, the second MS 25, the third MS 155) within the RFcoverage area 160 of the first MS 20. The timer field 210 may includetimer values that are associated with each hardware address in thehardware address field 205. For example, as seen in FIG. 12, thehardware address “00:A0:F8:23:EA:F7” has the timer value “5000”associated therewith. As noted above, the timer value may decrement tozero from a predetermined value (e.g., 45000 milliseconds), or incrementto a predetermined value. The timer field 210 may alternatively be theretransmission field, which counts a number of failed retransmissions.According to the present invention, once the timer value reaches a limitvalue (e.g., zero, predetermined number), the hardware addressassociated therewith, and thus, the wireless station, may be removedfrom the table 200. As such, the first MS 20 may no longer initiatecommunication with that wireless station using the second mode ofoperation. However, the hardware address previously removed may bere-added to the table 200 if the wireless station re-enters the RFcoverage area 160 of the first MS 20.

As would be understood by those skilled in the art, the wireless stationor device that has been manually paired with the first MS 20 may havethe timer value associated therewith set to a value that reflects such amanually pairing. For example, as shown in FIG. 12, the hardware address“00:0B:F2:00:10:60” has the timer value set to zero. This may indicatethat the hardware address should not be removed, unless done so manually(i.e., no decrement or increment to the timer value).

The table 200 may further include a sorted list 215 (e.g., a fixed arrayof pointers) to optimize searches and resorting of the table 200 when,for example, hardware addresses are added/removed. When the hardwareaddress needs to be found in the hardware address field 205, a binarysearch algorithm may be used on the sorted list 215 to quickly resolvethe presence of the searched for hardware address. Similarly, when a newhardware address is appended to the table 200, the sorted list 210 maybe re-organized to include the new hardware address. In this manner,less manipulation of a memory in the first MS 20 may be required.However, any search algorithm may be implemented based on the particularrequirements of an individual system.

Operation of the logic circuit, which checks the hardware address of thereceived data packet against the list of hardware addresses in the table200, is shown generally by the exemplary method 300 in FIG. 13. In step305, the second MS 25 receives the data packet from the wirelessstation. In step 310, the logic circuit in the second MS 25 checks thefourth address field 95 of the MAC frame 40 to determine whether thedata packet came from the AP 15 or the first MS 20. As would beunderstood by those skilled in the art, the second MS 25 may assume thatthe data packet came from another MS if the fourth address field 95 doesnot contain the hardware address of the AP with which the second MS 25is currently associated (e.g., the AP 15). If the data packet came fromthe AP 15, then the second MS 25 processes the MAC frame 40 in thenormal manner, as seen in step 325. However, if the data packet camefrom the first MS 20, as seen in step 315, then the second MS 25 checksits table 200 to determine if the hardware address of the first MS 25 isentered in the table 200. If the hardware address of the first MS 20 wasfound in the table 200, the timer value associated therewith is resetand the second MS 25 processes the MAC frame 40, as seen in step 325. Asseen in step 320, if the hardware address of the first MS 20 was not inthe table 200 of the second MS 25, then the hardware address is added tothe table 200 and the table 200 is resorted. As understood by thoseskilled in the art, resetting the timer value in step 325 and adding thehardware address in step 320 may enable the second MS 25 to initiatecommunication with the first MS 20 using the second mode of operation byassuming that the first MS 20 is within RF coverage area 165. The timervalue for the hardware address may be set via, for example, a managementinformation base (“MIB”) configuration parameter, and begins toincrement/decrement. In step 325, the MAC frame 40 is processed by thesecond MS 25.

A decision by the first MS 20 regarding which mode of operation to useis shown generally by the exemplary method 400 in FIG. 14. In step 405,the logic circuit determines whether the second mode of operation isenabled. If not enabled, the first MS 20 transmits the data packetaccording to the first mode of operation, as shown in step 410. If thesecond mode of operation is enabled, the method 400 proceeds to step415, wherein the logic circuit in the first MS 20 determines whether thehardware address of the destination MS (e.g., the second MS 25) islisted in the table 200 of the first MS 20. In step 420, if the hardwareaddress of the second MS 25 is not in the table 200, the data packet istagged to be sent to the AP 15. The first MS 20 then enables theauto-pairing by beginning to listen for the data packet destinationsignal 185 and/or the MS acknowledgment signal 190 within the RFcoverage area 160 and adds the hardware address of the second MS 25 toits table 200, as seen in step 425. If the hardware address of thesecond MS 25 is in the table 200 of the first MS 20, step 430, then thedata packet is tagged to be sent directly to the second MS 25. Asunderstood by those skilled in the art, tagging may be accomplished byinserting the hardware address of the AP 15 or second MS 25 into the MACframe 40.

An exemplary embodiment of a method 500 of transmission of the datapacket is shown in FIG. 15. In step 505, the first MS 20 determineswhether the data packet is tagged to be sent directly to the second MS25. If not, the first MS 20 transmits the data packet to the AP 15, asshown in step 510. If the data packet is tagged to be sent directly tothe second MS 25, step 515 shows that the first MS 20 sets a fallbacktimer. As understood by those skilled in the art, the fallback timer maydecrement from or increment to a predetermined value, which, whenreached, may cause the first MS 20 to retransmit the data packet to thesecond MS 25 or transmit the data packet to the AP 15. As those skilledin the art would understand, transmission of the data packet to the AP15 may include, for example, changing the hardware address in the fourthaddress field 95 and/or re-tagging the data packet to be sent to the AP15.

In step 520, the first MS 20 transmits the data packet to the second MS25. After transmission, as seen in step 525, the first MS 20 determineswhether it has received the MS acknowledgment signal 190 from the secondMS 25 before the fallback timer reaches the predetermined value. If theMS acknowledgment signal 190 has not been received by the first MS 20before the fallback timer reaches the predetermined value, the datapacket is transmitted to the AP 15, as shown in step 510. If the MSacknowledgment signal 190 has been received by the first MS 20, then itmay transmit the further data packet signal 195 directly to the secondMS 25 and reset the fallback timer (when not a manual pairing).

To further increase performance, the present invention may utilize therequest to send/clear to send (“RTS/CTS”) mechanism defined by the802.11 standard and well-known in the art. In this manner, the first MS20 may complete a RTS/CTS handshake before transmitting the data packetover the wireless network. Use of the handshake may provide positivecontrol over the wireless network and minimize collisions among wirelessstations that may be hidden.

An exemplary method 600 for automatically entering hardware addresses inthe table 200 is shown in FIG. 16. In step 605, the first MS 20 hearsthe wireless station transmitting within the RF coverage area 160. Aswould be understood by those skilled in the art, the wireless stationdoes not have to transmit to the first MS 20, but is simply transmittingthe data packet to another wireless station, which may be inside oroutside the RF coverage area 160 of the first MS 20.

In step 610, the first MS 20 determines whether the hardware address ofthe heard wireless station is currently included in the table 200. Ifthe hardware address is in the table 200, the first MS 20 may reset theassociated timer value. If the hardware address is not in the table 200,it is added to the table, as shown in step 615, and the timer value isset, as shown in step 620. The hardware address of the heard wirelessstation is maintained in the table 200 while the timer value isincremented/decremented. In step 625, the first MS 20 determines whetherthe timer value has reached the limit value, whereby the hardwareaddress of the heard wireless station may be removed from the table 200.

An exemplary embodiment of a pairing timer 700 used by the first MS willbe described with respect to FIG. 17. In one embodiment, the first MS 20may be active at all times, listening for other wireless stations withinthe RF coverage area 160. In a second embodiment, the first MS 20 may beactive only for intervals of time. As shown in FIG. 17, the pairingtimer 700 may include a first timer 705 and a second timer 710. Thefirst timer 705 may be used for passive listening. That is, the firsttimer 705 may activate the first MS 20 for a predetermined time (e.g.,3-5 beacon intervals). The first timer 705 may allow the first MS 20 tohear wireless stations within the RF coverage area 160, therebypopulating/updating the table 200 of the first MS 20. The first timer705 may subsequently deactivate the first MS 20 after predetermined orMIB-defined intervals (e.g., 10 beacon intervals). As would beunderstood by those skilled in the art, the number of beacon intervalsfor activation/deactivation of the receiver may be optimized dependingon the amount of traffic in the AP cell 35 and/or on the wirelessnetwork 10.

The second timer 710 may be used to activate the first MS 20 after thedata packet has been transmitted to the AP 15. In this manner, the firstMS 20 is activated to listen for the data packet destination signal 185from the AP 15 and/or the MS acknowledgment signal 190 from the secondMS 20 for a predetermined or MIB-defined interval (e.g., 5-7 times thecurrent beacon interval). As would be understood by those skilled in theart, the predetermined interval for listening for the signals 185,190may be modified to increase the probability of hearing the signals185,190 on the wireless network 10. Further optimization of thepredetermined interval may be accomplished by averaging times betweentransmission of the data packet source signals 175 and heard data packetdestination signals 185 and/or the MS acknowledgment signals 190.

The present invention further provides for power adjustment of the firstMS 20 (e.g., transmitting wireless station) by the second MS 25. Shownin FIG. 18 is an exemplary embodiment of a power adjustment mechanism800 which may be utilized by the second MS 25 (e.g., wireless stationreceiving the data packet). In an idle state 805, the second MS 25 isidle, listening for traffic within its RF coverage area 165. In a packetprocessing state 810, the second MS 25 has received the data packet andbegins packet processing. Along with standard packet processing, thelogic circuit of the second MS 25 will determine whether the data packetcame from the wireless station with its hardware address in the table200 of the second MS 25 or the wireless station without its hardwareaddress in the table 200 of the second MS 25. If the hardware address isnot present in the table 200, the processing moves back to the idlestate 805. If the hardware address is present in the table, the secondMS 25 moves into an existing source state 815.

In the existing source state 815, the subtype field 110 (shown in FIG.6) in the frame control field 65 is checked to determine if it containsa power adjust subtype, such as those shown in FIG. 8. If the subtypefield 110 does not contain the power adjust subtype, the processingmoves back to the idle state 805. If the subtype field 110 does containthe power adjust subtype, the processing moves to an entry update state820. Depending on the power adjust subtype, a power setting for the nexttransmission to the first MS 20 will be stored. For example, withreference to FIG. 8, the second MS 25 may indicate to the first MS 20 toincrease the power of a next transmission by including a subtype valueof “1000” in the subtype field 110.

The present invention further provides for power adjustment of thesecond MS 25 (e.g., receiving wireless station) by the first MS 20.Shown in FIG. 19 is an exemplary embodiment of a power adjustmentmechanism 900 which may be utilized by the first MS 20 (e.g., wirelessstation transmitting the data packet). In an idle state 905, the firstMS 20 is idle, waiting for the data packet to transmit. In a packetprocessing state 910, the data packet is going to be transmitted fromthe first MS 20. The logic circuit of the first MS 20 determines whetherthe data packet will be sent to a wireless station with its hardwareaddress in the table 200 of the first MS 25 or a wireless stationwithout its hardware address in the table 200 of the first MS 25. If thehardware address is not present in the table 200, the processing movesto a transmit packet state 920, where the data packet is transmitted. Ifthe hardware address is present in the table 200, the first MS 20 movesinto an existing destination state 915.

In the existing destination state 915, the hardware address of thesecond MS 25 has a previous received signal strength associatedtherewith. The previous received signal strength is compared with anoptimal received signal strength stored in the first MS 20. The subtypevalue in the subtype field 110 may be adjusted to reflect the differencein the previous strength and the optimal strength. For example, thefirst MS 20 may input a “1000” value thereby instructing the second MS25 to increase the power of its next transmission. When the subtypevalue has been adjusted, the processing moves to the transmit packetstate 920. When the transmission has been completed, the processingreturns to the idle state 905.

The present invention further provides a mechanism for encryptingcommunication using the second mode of operation. As known by thoseskilled in the art, encryption is a mechanism that encodes transmitteddata into a cipher-text to hide its meaning. In order for wirelessstations to communicate directly, they may use a common set ofencryption keys. For wireless stations that are paired manually, theencryption keys may be entered manually, as well. For wireless stationsthat are automatically paired, the process of associating with the AP 15requires that the correct encryption keys be in place.

The present invention further provides a mechanism for authentication,by which wireless stations accessing the wireless network 10 prove theiridentity. Manual pairing of wireless stations includes inherentauthentication, because a user pairing the wireless stationsauthenticates each. Automatic pairing of wireless stations is inherentin the processed and mechanisms described above, because the wirelessstation that desires access to the wireless network 10, at some point,authenticates itself to the network 10.

The present invention further provides a mechanism for layer managementwithin the 802.11 standard. Association is a service that establishes anAP/MS mapping that enables the wireless station to access thedistribution system. According to the present invention, the wirelessstation requiring access to the network 10, at some point, communicateswith the AP 15. Disassociation is a service that removes an existingassociation, which occurs when the wireless station leaves the network.According to the present invention, wireless stations may leave thenetwork 10 and remain paired. Re-association (i.e., roaming) is aservice that transfers an established association between the MS and theAP from the AP to a further AP. Re-association remains a viable servicewhen used in conjunction with the present invention. A synchronizationservice between the MSs 20,25 and the AP 15 is maintained through theabove-described mechanisms utilizing beacon intervals and deliverytraffic indication messages.

A further service provided by the present invention is power management.As is known in the art, the MSs will go into sleep mode when they areinactive for a predefined period of time. Therefore, the MSs may neverbe heard by other MSs listening to activity in the wireless network 10.According to the present invention, the MS enters a modified sleep mode,whereby it periodically transmits a NULL data packet, or “chirps.” Thechirps allow other wireless stations within the RF coverage area of theMS to establish communication therewith using the second mode ofoperation. As would be understood by those skilled in the art, theperiodicity of the NULL data packet transmissions may be varied and/orset at arbitrary values.

The second mode of operation provides advantages not available whenusing solely the first mode of operation. For instance, the second modeof operation may increase the capacity of the system 5. As is known inthe art, during a distributed coordination function (“DCF”), wirelessstations (e.g., MSs, APs and any other wireless devices) contendtemporally for access to the wireless network 10. The wireless stationsuse a network access mechanism, such as a carrier sense multiple accesswith collision avoidance (“CSMA/CA”) or a carrier sense multiple accesswith collision detection (“CSMA/CD”). CSMA/CA is a technique where thewireless station wishing to access the wireless network 10 listens toactivity on the wireless network 10 before attempting a transmission.Activity on the wireless network 10 is derived from a carrier sensingmechanism provided by a physical layer of the 802.11 standard, which isknown to those skilled in the art. By using CSMA/CA, the wirelessstation attempts to avoid collisions with activity on the wirelessnetwork by listening, rather than reacting to collisions detected (i.e.,CSMA/CD).

Another advantage provided by the second mode of operation is adecreased time for transmission of the data packet. As mentioned above,the minimum number of hops for transmission of the data packet is twohops. However, in the second mode of operation, the data packet istransmitted in one hop, because transmission through the AP 15 has beeneliminated. Direct communication between the first MS 20 and the secondMS 25 may increase overall throughput of the system 5, reduce latency oftransmission of the data packet and reduce aggregate power of the system5 which is consumed by transmission of the data packet. As understood bythose skilled in the art, power consumption has an inverselyproportional relationship with battery life. Thus, reduction of theaggregate power may extend the battery life.

A further advantage provided by the second mode of operation is adecrease in an amount of noise present on the wireless network 10. Aswell as reducing traffic, transmissions between the first MS 20 and thesecond MS 25 may use a lower power because the MSs 20,25 may be within aclose range. Close range communication may reduce interference withinthe wireless network 10.

The above-described advantages are simply illustrative, and by no meansexhaustive of the benefits of the present invention. The presentinvention may be further utilized in a person-to-person (“P2P”) voicesystem, a P2P priority system and a P2P communication system whichutilizes a mesh network.

The present invention has been described with the reference to the MSs20,25, the AP 15, and the RF coverage areas 160,165. One skilled in theart would understand that the present invention may also be successfullyimplemented. Accordingly, various modifications and changes may be madeto the embodiments without departing from the broadest spirit and scopeof the present invention as set forth in the claims that follow. Thespecification and drawings, accordingly, should be regarded in anillustrative rather than restrictive sense.

1. A system, comprising: a mobile station; and an access pointconnecting the mobile station to a network; wherein the mobile stationhas a first mode of operation and a second mode of operation, the firstmode of operation comprising the mobile station transmitting a datapacket intended for a further mobile station to the access points andthe access point transmitting the data packet to the further mobilestation, and the mobile station listening for the data packettransmission from the access point to the further mobile station and theassociated acknowledgement from the further mobile station to the accesspoint, the second mode of operation comprising the mobile stationtransmitting the data packet intended for the further mobile stationdirectly to the further mobile station when the address of the furthermobile station is present in the table of the mobile station.
 2. Thesystem according to claim 1, wherein the mobile station includes a tableto store a hardware address of the further mobile station.
 3. The systemaccording to claim 2, wherein the hardware address has a timer valueassociated therewith.
 4. The system according to claim 3, wherein themobile station initiates communication with the further mobile stationusing the second mode of operation before an expiration of the timervalue.
 5. The system according to claim 2, wherein the mobile station inthe first mode of operation adds the hardware address of the furthermobile station to the table and resets a timer value associatedtherewith, when one of the listened for transmissions is detected. 6.The system according to claim 1, wherein the mobile station switchesfrom the first mode of operation to the second mode of operation whenthe further mobile station enters a radio frequency coverage area of themobile station.
 7. The system according to claim 1, wherein the furthermobile station uses the first mode of operation and the second mode ofoperation to transmit a further data packet to the mobile station. 8.The system according to claim 7, wherein the further mobile stationincludes a table to store a hardware address of the mobile station.
 9. Asystem, comprising: a mobile station; and an access point connecting themobile station to a network: wherein the mobile station has a first modeof operation and a second mode of operation, the first mode of operationcomprising the mobile station transmitting a data packet intended for afurther mobile station to the access point and the access pointtransmitting the data packet to the further mobile station, the secondmode of operation comprising the mobile station transmitting the datapacket intended for the further mobile station directly to the furthermobile station; wherein the mobile station includes a table to store ahardware address of the further mobile station, wherein the hardwareaddress has a timer value associated therewith, wherein, when the timervalue reaches a limit value, the hardware address is removed from thetable.
 10. A system, comprising: a mobile station; and an access pointconnecting the mobile station to a network; wherein the mobile stationhas a first mode of operation and a second mode of operation, the firstmode of operation comprising the mobile station transmitting a datapacket intended for a further mobile station to the access point and theaccess point transmitting the data packet to the further mobile station,the second mode of operation comprising the mobile station transmittingthe data packet intended for the further mobile station directly to thefurther mobile station; wherein the mobile station switches from thefirst mode of operation to the second mode of operation when the mobilestation hears an acknowledgment signal transmitted from the furthermobile station to the access point.
 11. A system, comprising: a mobilestation; and an access point connecting the mobile station to a network;wherein the mobile station has a first mode of operation and a secondmode of operation, the first mode of operation comprising the mobilestation transmitting a data packet intended for a further mobile stationto the access point and the access point transmitting the data packet tothe further mobile station, the second mode of operation comprising themobile station transmitting the data packet intended for the furthermobile station directly to the further mobile station; wherein themobile station operates in the second mode of operation to transmit thedata packet to the further mobile station and operates in the first modeof operation to transmit data packets to additional mobile stationswithout leaving the second mode of operation.
 12. A mobile station,comprising: a processor; and a memory storing a set of instructions forexecution on the processor; wherein the set of instructions comprises afirst mode of operation and a second mode of operation, the first modeof operation comprising the mobile station transmitting a data packetintended for a further mobile station to an access point connected to anetwork, the access point transmitting the data packet to the furthermobile station, and the mobile station listening for the data packettransmission from the access point to the further mobile station and theassociated acknowledgement from the further mobile station to the accesspoint, the second mode of operation comprising the mobile stationtransmitting the data packet intended for the further mobile stationdirectly to the further mobile station when the address of the furthermobile station is present in the table.
 13. The mobile station accordingto claim 12, wherein the mobile station includes a table to store ahardware address of the further mobile station.
 14. The mobile stationaccording to claim 13, wherein the hardware address has a timer valueassociated therewith.
 15. The mobile station according to claim 13,wherein the mobile station in the first mode of operation adds thehardware address of the further mobile station to the table and resets atimer value associated therewith, when one of the listened fortransmissions is detected.
 16. A mobile station, comprising: aprocessor; and a memory storing a set of instructions for execution onthe processor; wherein the set of instructions comprises a first mode ofoperation and a second mode of operation, the first mode of operationcomprising the mobile station transmitting a data packet intended for afurther mobile station to an access point connected to a network, theaccess point transmitting the data packet to the further mobile station,the second mode of operation comprising the mobile station transmittingthe data packet intended for the further mobile station directly to thefurther mobile station; wherein the mobile station includes a table tostore a hardware address of the further mobile station, wherein thehardware address has a timer value associated therewith, wherein whenthe timer value reaches a limit value, the hardware address is removedfrom the table.
 17. A mobile station, comprising: a processor; and amemory storing a set of instructions for execution on the processor;wherein the set of instructions comprises a first mode of operation anda second mode of operation, the first mode of operation comprising themobile station transmitting a data packet intended for a further mobilestation to an access point connected to a network, the access pointtransmitting the data packet to the further mobile station, the secondmode of operation comprising the mobile station transmitting the datapacket intended for the further mobile station directly to the furthermobile station; wherein the mobile station operates in the first mode ofoperation to transmit data packets to additional mobile stations withoutleaving the second mode of operation.
 18. A method, comprising: checkinga data packet transmitted to a mobile station; checking a field of amedia access control frame when the data packet is from a mobile stationwith its hardware address present in the table of the mobile stationthat received the data packet; adjusting transmission power of themobile station based on a value in the field; and transmitting a nextmedia access control frame using the adjusted transmission power. 19.The method according to claim 18, wherein the field is one of a typefield and a subtype field.
 20. A method, comprising: sending a datapacket destined for a mobile unit to an access point; listening for oneof a transmission of the data packet by the access point to the mobileunit and a transmission of an acknowledgment by the mobile unit to theaccess point; adding an address of the mobile unit to a table when theone of the listened for transmissions is detected; and sending a furtherdata packet destined for the mobile unit directly to the mobile unitwhen the address is present in the table.
 21. The method according toclaim 20, wherein the address is a media access control address.
 22. Themethod according to claim 20, further comprising removing the addressfrom the table when a timer value associated with the address expires.23. The method according to claim 20, further comprising receiving anacknowledgment from the mobile unit after the mobile unit has receivedthe further data packet.
 24. The method according to claim 20, furthercomprising resending the further data packet to the mobile unit when atimer expires before reception of an acknowledgment.
 25. The methodaccording to claim 20, further comprising resending the further datapacket to the access point when a timer expires before reception of anacknowledgment.